Researchers continue to make solid progress in the development of gene therapies to clear out aggregations of unwanted compounds in our bodies: "Alzheimer's involves a protein called amyloid-beta, which makes up gooey clots or plaques that form in the brain. These toxic clumps, along with accessory tangled fibers, kill brain cells and interfere with memory and thinking. The situation has been compared to a build-up of cholesterol in coronary arteries. ... Delivery of genes that led to production of an enzyme that breaks up amyloid showed robust clearance of plaques in the brains of the mice ... The gene delivery technique employed by the research team has been used in several other trials with animals that model human diseases, including cancers. The procedure involves removing cells from patients, making genetic changes, and then putting back the modified cells, which should treat a disease or disability. So far, this approach has produced encouraging results for cancers, blood, muscle, and eye diseases, spinal cord injuries, stroke, Parkinson's and Huntington diseases, and amyotrophic lateral sclerosis."

Link: http://www.news.harvard.edu/gazette/2007/09.13/99-alzheimers.html